Vehicles that have dual driver controls are used in various industries, such as the recycling industry. For example, a truck that collects recyclable materials from residential areas is often operated by a single person who must both drive the vehicle from stop to stop and also get out at each stop to load the curbside collection into collection bins on the vehicle. Since curbside collections may take place on either or both the right and left sides of a street depending on the nature of the neighborhood bordering the street and on the direction of travel of a recycling truck along the street, a vehicle that has both right- and left-side driver stations each equipped with its own set of driver controls should enable a single person to perform this collection service with greater overall efficiently than if the vehicle had only a single driver station on one particular side.
Such dual-control vehicles which have engines that are operated strictly by mechanical controls typically employ respective mechanical linkages linking their respective driver controls to the engine. Thus for example, dual accelerator pedals are mechanically linked together to the engine so that either pedal by itself is capable of accelerating the engine. In a vehicle having an electronically-controlled engine, the accelerator pedal does not act directly on the engine, but instead acts on an accelerator pedal sensor that provides an input to an electronic controller that in turn accelerates the engine based on the accelerator pedal sensor input. The electronic controller may also at times take into account certain inputs from other sources as it accelerates the engine.
While it may be possible to link dual accelerator pedals together so that either one is capable of operating a single accelerator pedal sensor, the present invention provides a better solution to the problem of equipping an electronically-controlled engine with dual accelerator pedal controls because it employs existing accelerator pedal sensors that are currently used in single accelerator pedal control of an electronically-controlled engine.
A typical existing accelerator pedal sensor comprises a housing that contains a pedal position sensing device and an idle validation switch that are operated by a mechanical input from an accelerator pedal that is external to the housing. This mechanical input is typically a crank or lever, and the pedal position sensing device is typically a potentiometer. The wiper of the potentiometer is mechanically operated by the pedal, and it is electrically coupled to the electronic controller so that the potentiometer supplies to the controller a voltage whose magnitude represents pedal position over a range spanning idle and non-idle positions. The idle validation switch serves to distinguish idle position from non-idle positions, and it is coupled with the electronic controller so that the controller can detect whether the switch is in open or closed condition. One switch condition indicates that the pedal is in idle position while the other switch condition indicates that the pedal is in non-idle position.
The invention comprises the use of two such accelerator pedal sensors like the one just described, one sensor for each pedal, and a coupling circuit means, including a diode network, for coupling the two sensors with the electronic controller. The diode network serves two purposes: 1) to assure that the sensor whose accelerator pedal is more distant from idle is actively connected to the controller to the exclusion of the other sensor, and 2) to assure that the other sensor imposes no current drain on the actively connected sensor that might otherwise impair the accuracy of the input that the actively-connected sensor is furnishing to the controller. The diodes can be incorporated into the wiring harness that couples the sensors with the controller so that neither the controller nor the sensors has to be modified for a dual-control configuration.
The foregoing, along with further features, advantages, and benefits of the invention, will appear in and from the following detailed description of a presently preferred embodiment representing the best mode contemplated at this time for carrying out the invention.